1. Field of the Invention
The present invention relates to a scroll of a gas turbine, and more particularly, to a scroll of a gas turbine in which the structure of the air path for cooling the scroll is improved.
2. Description of the Related Art
As shown in FIG. 1, a typical gas turbine engine used as an engine for industrial use includes compressors 10a and 10b for compressing external air A multiple times, a combustor 13 inside a casing for generating gas of high temperature and high pressure in a liner 12 by injecting and igniting fuel through a nozzle 14 to compressed air supplied from an outlet 10c of the compressors 10a and 10b, and a turbine 16 for generating a rotation force using a high pressure gas generated from the combustor.
The gas generated from the combustor 13 is provided to rotate a wheel (not shown) of the turbine 16 having a plurality of blades. A scroll 20 is related to the design of a path which appropriately guides the flow of gas.
Referring to FIG. 2, the scroll 20 includes a scroll main body 21 connected to the combustor 13 via the liner 12 and forming an annular space 28, and guiding scrolls 25 and 26 connected to an opening at one side of the scroll main body 21 and extending toward the blade of the turbine 16, forming a nozzle 27 through which gas of high temperature and high pressure flowing in the annular space 28 is injected. As combustion gas of very high temperature flows in the scroll 20, a cooling structure to cool the scroll is needed. For this, scroll housings 22, 23 and 24 are installed outside the scroll main body 21 and the guiding scrolls 25 and 26, at a predetermined gap, and cooling air flows through the gap formed between the scroll housings 22, 23 and 24 and the scroll main body 21 and the guiding scrolls 25 and 26. As shown in FIG. 2, the cooling air flowing around the scroll 20 comes into the gap through holes formed in the scroll housings 22, 23 and 24 to cool the scroll 20.
The air supplied from the compressors 10a and 10b is mainly used as the cooling air needed in the above cooling method. Arrows shown in FIG. 1 indicate the flow of the air flowing to the gas turbine. When the external air A is compressed by the compressors 10a and 10b and comes out through the compressor outlet 10c, most of the air is supplied to the casing 11 and the combustor 13 through a path formed outside the liner 12 and burned with the fuel. The remaining portion of the air is used for cooling of the scroll 20 while flowing around the scroll 20.
Thus, in the scroll of the conventional gas turbine having the above structure, as only an extremely small portion of the compressed air is used for cooling, the efficiency of cooling is lowered so that an increase in temperature of the scroll is not appropriately prevented and thus durability of the scroll is lowered.